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Am. J. Hum. Genet. 70:244–250, 2002 Report

Mapping of Charcot-Marie-Tooth Disease Type 1C to 16p Identifies a Novel Locus for Demyelinating Neuropathies Valerie A. Street,1 Jeff D. Goldy,2 Alana S. Golden,5 Bruce L Tempel,1 Thomas D. Bird,3,4,6 and Phillip F. Chance2,3 1V. M. Bloedel Hearing Research Center, Department of Otolaryngology–Head and Neck Surgery, 2Departments of Pediatrics, 3Neurology, and 4Medicine, and 5Undergraduate Neurobiology Research Program, University of Washington, and 6VA Puget Sound Health Care System, Seattle

Charcot-Marie-Tooth (CMT) neuropathy represents a genetically heterogeneous group of diseases affecting the peripheral nervous system. We report genetic mapping of the disease to chromosome 16p13.1-p12.3, in two families with autosomal dominant CMT type 1C (CMT1C). Affected individuals in these families manifest characteristic CMT symptoms, including high-arched feet, distal muscle weakness and atrophy, depressed deep-tendon reflexes, sensory impairment, slow nerve conduction velocities, and nerve demyelination. A maximal combined LOD score of 14.25 was obtained with marker D16S500. The combined haplotype analysis in these two families localizes the CMT1C within a 9-cM interval flanked by markers D16S519 and D16S764. The disease-linked haplotypes in these two pedigrees are not conserved, suggesting that the gene mutation underlying the disease in each family arose independently. The epithelial membrane 2 gene (EMP2), which maps to chromosome 16p13.2, was evaluated as a candidate gene for CMT1C.

Charcot-Marie-Tooth disease (CMT; also known as “he- 145900), also known as “Dejerine-Sottas disease,” may reditary motor and sensory neuropathy”) is a group of be inherited as an autosomal recessive or autosomal disorders characterized by degenerative changes in pe- dominant trait and is characterized by severe hypomye- ripheral motor and sensory nerves. CMT is transmitted lination, markedly reduced NCVs, and infantile onset most frequently in an autosomal dominant manner and (Lyon 1969; Kennedy et al. 1977). CMT4 is inherited affects ∼1 in 2,000 individuals (Skre 1974), making it as an autosomal recessive trait, with patients displaying one of the most common inherited neurological diseases. early disease onset and rapid distal limb atrophy (Ben CMT leads to progressive distal muscle weakness af- Othmane et al. 1993). In addition to autosomal forms fecting the upper and lower limbs, with loss of sensation. of CMT, X-linked dominant inheritance also has been Clinical signs may range from a lack of symptoms to well characterized (Bergoffen et al. 1993). marked muscle weakness, and, in rare cases, patients On the basis of genetic-linkage and gene-sequence may become wheelchair dependent. analysis, CMT1 has been divided into four subtypes. CMT type I (CMT1) is characterized by demyelina- CMT1A (MIM 118220) is associated with a 1.4-Mb tion and reduced (!40 m/s) nerve conduction velocities duplication on chromosome 17p11.2-p12 (Lupski et al. (NCVs) (Dyck and Lambert 1968). In CMT type II 1991; Raeymaekers et al. 1991) with a gene-dosage ef- fect for peripheral myelin protein (PMP-22 [MIM (CMT2), there is axonal loss, with normal or only mildly 601097]) (Matsunami et al. 1992; Patel et al. 1992; Tim- reduced NCVs (Dyck and Lambert 1968). CMT3 (MIM merman et al. 1992; Valentijn et al. 1992b; Warner et Received August 3, 2001; accepted for publication October 5, 2001; al. 1996). PMP-22 point mutations have been found in electronically published November 16, 2001. rare patients with CMT1A who lack the duplication Address for correspondence and reprints: Dr. Phillip Chance, Di- (Valentijn et al. 1992a; Roa et al. 1993; Nelis et al. vision of Genetics and Development, Department of Pediatrics, 1994). CMT1B (MIM 118200) results from mutations Box 356320, University of Washington, Seattle, WA 98195. E-mail: in the gene on chromosome 1 encoding myelin protein [email protected] ᭧ 2002 by The American Society of Human Genetics. All rights reserved. zero (MPZ [MIM 159440]; also known as “Po pro- 0002-9297/2002/7001-0023$15.00 tein”), a major structural protein of peripheral mye-

244 Figure 1 Haplotype analysis in pedigrees K1550 (A) and K1551 (B). Affected individuals are denoted by blackened symbols, males are denoted by squares, females are denoted by circles, and deceased persons are indicated by a diagonal line through a symbol. Markers are listed from telomere (top) to centromere (bottom) and are the same in both pedigrees. The CMT1C-linked haplotype is boxed. 246 Am. J. Hum. Genet. 70:244–250, 2002

Table 1 Pedigrees K1550 and K1551: LOD Scores with Chromosome 16p Markers

LOD SCORE AT RECOMBINATION FRACTION (v) p MARKER (POSITION) a AND PEDIGREE .0 .01 .05 .1 .2 .3 .4 Zmax vmax D16S404 (16.7): K1550 Ϫϱ .46 1.56 1.79 1.60 1.11 .53 1.793 .114 K1551 Ϫϱ 3.07 4.03 4.07 3.44 2.43 1.18 4.105 .076 K1550ϩK1551 Ϫϱ 3.53 5.59 5.86 5.04 3.54 1.71 D16S519 (19.7): K1550 3.62 4.83 5.07 4.78 3.83 2.65 1.34 5.083 .038 K1551 Ϫϱ 3.37 3.70 3.53 2.80 1.86 .80 3.706 .046 K1550ϩK1551 Ϫϱ 8.20 8.77 8.31 6.63 4.51 2.14 D16S307 (21.8): K1550 3.27 3.20 2.91 2.54 1.81 1.11 .50 3.270 .000 K1551 4.07 4.00 3.71 3.32 2.47 1.56 .66 4.070 .000 K1550ϩK1551 7.34 7.20 6.62 5.86 4.28 2.67 1.66 D16S310 (23.1): K1550 5.74 5.64 5.25 4.74 3.67 2.53 1.32 5.740 .000 K1551 5.58 5.48 5.06 4.51 3.35 2.11 .84 5.580 .000 K1550ϩK1551 11.32 11.12 10.31 9.25 7.02 4.64 1.40 D16S500 (27.0): K1550 6.97 6.86 6.39 5.80 4.53 3.16 1.67 6.970 .000 K1551 7.28 7.15 6.64 5.96 4.53 2.96 1.3 7.280 .000 K1550ϩK1551 14.25 14.01 13.03 11.76 9.06 6.12 2.97 D16S764 (28.7): K1550 Ϫϱ 3.59 3.92 3.76 3.08 2.21 1.19 3.923 .047 K1551 2.93 2.89 2.69 2.41 1.79 1.07 .35 2.930 .000 K1550ϩK1551 Ϫϱ 6.48 6.61 6.17 4.87 3.28 1.54 D16S310 (31.1): K1550 Ϫϱ 4.00 4.31 4.10 3.32 2.35 1.25 4.310 .043 K1551 Ϫϱ Ϫ.26 .89 1.16 1.06 .70 .31 1.180 .125 K1550ϩK1551 Ϫϱ 3.74 5.20 5.26 4.38 3.05 1.56 a Markers are shown in order given by Dib et al. (1996), from telomere to centromere. Marker map positions (in cM) are based on the Ge´ne´thon and Marshfield human sex-averaged linkage maps. lin (reviewed by Lupski [1998]). The CMT1C (MIM for CMT1, including distal muscle weakness and atro- 300200) designation was suggested on the basis of ge- phy, depressed deep-tendon reflexes, and sensory im- netic evidence, when linkage to regions on pairment (Dyck and Lambert 1968). The mean ulnar 17 and 1 were excluded in two CMT1 pedigrees (K1550 (16.7 m/s [n p 3 ] and 25.3 m/s [n p 8 ], for K1550 and and K1551) (Chance et al. 1990, 1992). The CMT1D K1551, respectively), median (23 m/s [n p 5 ] and 25.8 gene maps to chromosome 10 and is associated with m/s [n p 12 ]), and peroneal (20.4 m/s [n p 4 ], 21 m/s mutations in the early growth response 2 gene (EGR2 [n p 6 ]) motor-nerve conduction velocities of affected [MIM 129010]), also known as “Krox-20” (Warner et K1550 and K1551 individuals are consistent with al. 1998). In the present article, we describe the mapping CMT1. One affected person (individual 2.7) in pedigree of the CMT1C locus to and the eval- K1550 was examined further, by sural-nerve biopsy, uation of the epithelial membrane protein 2 gene (EMP2 which demonstrated “onion bulb hypertrophy” typical [MIM 602334]) as a candidate gene. of demyelinating CMT. Under a protocol of informed consent approved by A genomewide scan (ABI PRISM Linkage Mapping the institutional review board of the University of Wash- Set Version 2; PE Biosystems) was performed in pedi- ington, Seattle, 15–20 ml of blood were drawn, by ve- grees K1550 and K1551, with informative microsatellite nipuncture, to obtain high-molecular-weight DNA, as markers (Dib et al. 1996) spaced at ∼10-cM intervals. described previously (Neitzel 1986). Pedigrees K1550 PCR was performed under the conditions recommended and K1551 are of Irish and English descent, respectively, by the manufacturer (PE Biosystems). PCR products and are depicted in figures 1A and B, respectively. Male- were multiplexed and separated by capillary electropho- to-male transmission is observed in both families, con- resis using an ABI PRISM 310 Genetic Analyzer (PE firming autosomal dominant inheritance. Affected in- Biosystems). Microsatellite marker-allele data were an- dividuals in both pedigrees met widely accepted criteria alyzed by GENESCAN version 3.1.2 and GENOTYPER Reports 247

16p13.1-p12.3, in both pedigrees (table 1). Haplotype analysis indicated that three markers—D16S3075, D16S3102, and D16S500—were nonrecombinant with the CMT1C phenotype in family K1550 (fig. 1A). In- dividual 2.4 displayed a crossover between markers D16S519 and D16S3075, defining D16S519 as a distal flanking marker. Individual 3.2 displayed a crossover between markers D16S500 and D16S764, defining D16S764 as a proximal flanking marker. In pedigree K1551, haplotype analysis determined that four mark- ers—D16S3075, D16S3102, D16S500, and D16S764 —were nonrecombinant with the CMT1C phenotype (fig. 1B). Individual 3.8 demonstrated a crossover be- tween markers D16S519 and D16S3075, confirming D16S519 as a distal flanking marker. Individuals 3.2, 3.13, and 4.4 showed crossovers between markers D16S764 and D16S3103. The combined analysis in these two families suggests that the CMT1C gene maps within a 9-cM interval between markers D16S519 and D16S764 (fig. 2). Although no public human-genome database contains contiguous sequence that spans mark- Figure 2 CMT1C-containing region of 16p. The CMT1C ge- ers D16S519 and D16S764, available sequence infor- netic interval on chromosome 16p13.1-p12.3 is indicated by a bracket mation indicates the presence of у20 in this in- ( ] ), with flanking markers shown in boldface. Marker map order and terval on chromosome 16p. position are based on the Ge´ne´thon and Marshfield human sex-av- EMP2 has been mapped to chromosome 16p13.2 eraged linkage maps. The approximate location of EMP2, based on (Liehr et al. 1999) and is a member of the PMP-22 gene previous radiation hybrid mapping, is indicated by a brace ( } ). family (Taylor and Suter 1996). Given the coincident map position of EMP2 and CMT1C, the coding exon version 2.0 (PE Biosystems). Amplification products gen- and flanking intron nucleotide sequence for EMP2 erated with the ABI panel sets were sized according to (GenBank accession numbers NT_019611 and X94770) CEPH control DNA (1347-02) and were assigned allele were compared between affected and unaffected family numbers consistent with the Marshfield and CEPH des- members in pedigrees K1550 and K1551 (table 2), but ignations (Center for Medical Genetics, Marshfield Med- no disease-associated mutations were detected. An ical Research Foundation Web site; Fondation Jean EMP2 C/T single-nucleotide polymorphism (SNP) is pre- Dausset–CEPH Web site). New alleles not reported in sent 14 bp 5 of the AG splice-acceptor site in the third the CEPH database include a 205-bp product (desig- coding exon. Some affected individuals in both pedigrees nated “allele 9” in the present study) for marker are heterozygous at the C/T SNP, suggesting that the D16S500, a 202-bp product (designated “allele 9”) for EMP2 gene is not deleted in individuals with CMT1C. marker D16S3075, and a 159-bp product (designated In an effort to genetically map EMP2 relative to “allele 10”) for marker D16S519. Two markers, CMT1C, we directly sequenced this area in key individ- D16S764 and D16S519, were obtained from Research uals (2.4 and 3.7 from K1500 and 3.7, 3.8, 4.5, and 4.6 Genetics. Under a model of autosomal dominant inher- from K1551), including those displaying crossover itance, pairwise LOD scores were calculated using the events between D16S519 and D16S3075. The C/T SNP LINKAGE computer program package version 5.1 (La- was uninformative in family K1551, since affected in- throp et al. 1985). Equal recombination rates in males dividual 3.8 was T/T homozygous. In pedigree K1550, and females were assumed, and a CMT1-gene frequency the genotype of unaffected individual 1.2 was T/T, and of 0.0005 (Skre 1974) was used for the calculations. three of her affected offspring (2.2, 2.4, and 2.7) were Equal microsatellite marker-allele frequencies were em- C/T heterozygous, suggesting that the C allele was car- ployed in the analyses, unless CEPH allele frequencies ried on the affected chromosome inherited from the fa- were available. Haplotypes were constructed on the ba- ther (1.1). Individual 2.4 transmitted the C allele to her sis of known marker orders (Dib et al. 1996). affected daughter (3.7). Inheritance of the C/T SNP in

A combined maximal LOD score (Zmax) of 14.25 was family K1550 suggests that EMP2 is contained within obtained with marker D16S500, establishing linkage to the nonrecombinant CMT-linked haplotype and that it 1 chromosome 16. Significant LOD scores (Zmax 3 ) were therefore cannot be eliminated as a candidate gene on obtained with multiple markers from chromosome the basis of map position alone. 248 Am. J. Hum. Genet. 70:244–250, 2002

Table 2 Genomic Intronic Primer Sequences to Amplify EMP2 Coding Exons

PCR PRIMER PRODUCT ANNEALING (5 r3 ) CODING SIZE TEMPERATURE EXON Forward Reverse (bp) (ЊC) 1 actgcaggtatgacgacc acctagtctctggtatgc 487 60 2 acctcctgagtcagtctgc ggagtatgcagtgagtgg 367 65 3 tgctcagaccatgtagacg acgtcccactgtggtacagc 488 65 4 tacccagggtgcactgtgg gaatgtggattctgtactgc 291 65

The bifunctional apoptosis regulator gene (BAR) is an- or chromosome 16 gene mutations. We cannot predict other potential candidate gene for CMT1C. BAR appears the contribution that CMT1C gene mutations will make to encode a scaffold protein that is able to modulate both to the remaining 30% of CMT1 cases. However, it is (1) the extrinsic apoptotic pathway activated by extra- noteworthy that two unrelated families with CMT1C cellular ligands binding to membrane-spanning tumor- that have been discussed in the present article were iden- necrosis–factor receptors and (2) the intrinsic apopto- tified in a limited geographical region of the Pacific tic pathway triggered by mitochondrial release of cy- Northwest. The CMT1C-linked haplotypes—4-3-4-2-9- tochrome c (Zhang et al. 2000). Like BAR, the PMP-22 1-3 in K1550 and 5-4-3-1-1-2-7 in K1551—are not con- gene underlying CMT1A also regulates programmed cell served, suggesting that the gene mutation underlying the death (Brancolini et al. 1999). disease in each family arose independently; this raises CMT demonstrates extensive genetic heterogeneity, the possibility that mutations in the CMT1C gene might with nine different genes thus far identified that, when not be rare. Discovery of the CMT1C gene will allow altered, can give rise to a CMT phenotype. These CMT investigators to determine the contribution of CMT1C genes are PMP-22, MPZ, EGR2, the connexin-32 gene gene mutations to the 30% of CMT1 cases not ac- (Cx-32 [MIM 304040]), the neurofilament-light gene counted for by the duplication of PMP-22 and will fur- (NF-L [MIM 162280]) (Mersiyanova et al. 2000; De ther our understanding of the basic processes controlling Jonghe et al. 2001), the myotubularin-related protein 2 myelination. gene (MTMR2 [MIM 603557]) (Bolino et al. 2000), N-myc downstream-regulated gene 1 (NDRG1 [MIM 605262]) (Kalaydjieva et al. 2000), the periaxin gene Acknowledgments (PRX [MIM 605725]) (Boerkoel et al. 2001; Guilbot et We thank the participating families for their cooperation al. 2001), and the b isoform of kinesin superfamily mo- throughout this study. During this study, postdoctoral funding tor protein B gene (KIF1Bb) (Zhao et al. 2001). The was provided to V.A.S. by the Charcot-Marie-Tooth Associ- encoded by these genes are involved in a variety ation, the Muscular Dystrophy Association, and National In- of cellular functions, including cytoskeletal scaffolding stitutes of Health Genetic Approaches to Aging Research (in the case of NF-L), the transport of small molecules Training Grant AG00057. Undergraduate research funding was provided to A.S.G. by the Mary Gates Research Foun- within and across the myelin sheath (in the case of Cx- dation. This study was funded by a Muscular Dystrophy As- 32), signal transduction (in the case of MTMR2), cell sociation Research Grant (to P.F.C.); National Institutes of arrest/proliferation and differentiation (in the case of Health grants NS38181 (to P.F.C.), DC02739 (to B.LT.), and PMP-22, NDRG1, and EGR2), myelin maintenance HD02274 (to the Center on Human Development and Disa- and formation (in the case of MPZ and PRX) (Gilles- bility–Genetics Core, University of Washington); and research pie et al. 2000), and axonal transport (in the case of funds from the VA Puget Sound Health Care System (to KIF1Bb). T.D.B.). We appreciate the excellent technical support provided In the present study, we have firmly established the by Hillary Lipe, R.N., and Kathy O’Briant, M.S. Dr. Jerry category of CMT1C and have identified an additional Schellenberg provided access to an ABI Prism 310 Genetic locus for CMT, on chromosome 16. Therefore, patients Analyzer during the early stages of this study. We thank Drs. diagnosed clinically with CMT1 may have alterations in Craig Bennett, Giles Watts, and Jan Meuleman for advice and comments on the manuscript. PMP-22 (in the case of CMT1A), MPZ (in the case of CMT1B), an unidentified gene on chromosome 16 (in the case of CMT1C), or EGR2 (in the case of CMT1D). Electronic-Database Information The CMT1A duplication on chromosome 17p11.2-p12, Accession numbers and URLs for data in this article are as which contains PMP-22, accounts for ∼70% of all cases follows: of CMT1 (Wise et al. 1993). The remaining 30% of CMT1 cases may be caused by PMP-22, MPZ, EGR2, Center for Medical Genetics, Marshfield Medical Research Reports 249

Foundation, http://www.marshfieldclinic.org/research/ sory neuron diseases with peroneal muscular atrophy. I. genetics/ Neurologic, genetic and electrophysiologic findings in he- Fondation Jean Dausset–CEPH, http://www.cephb.fr/ reditary polyneuropathies. Arch Neurol 18:603–618 GenBank, http://www.ncbi.nlm.nih.gov/Genbank/ (for EMP2 Gillespie CS, Sherman DL, Fleetwood-Walker SM, Cottrell DF, genomic and cDNA [accession numbers NT_019611 and Tait S, Garry EM, Wallace VC, Ure J, Griffiths IR, Smith X94770, respectively]) A, Brophy PJ (2000) Peripheral demyelination and neuro- Ge´ne´thon, http://www.genethon.fr/ pathic pain behavior in periaxin-deficient mice. Neuron 26: Online Mendelian Inheritance in Man (OMIM), http://www 523–531 .ncbi.nlm.nih.gov/Omim/ (for CMT1C [MIM 601098], Guilbot A, Williams A, Ravise N, Verny C, Brice A, Sherman EMP2 [MIM 602334], CMT3 [MIM 145900], CMT1A DL, Brophy PJ, LeGuern E, Delague V, Bareil C, Megarbane [MIM 118220], CMT1B [MIM 118200], PMP-22 [MIM A, Claustres M (2001) A mutation in periaxin is responsible 601097], MPZ [MIM 159440], EGR2 [MIM 129010], Cx- for CMT4F, an autosomal recessive form of Charcot-Marie- 32 [MIM 304040], NF-L [MIM 162280], MTMR2 [MIM Tooth disease. Hum Mol Genet 10:415–421 603557], NDRG1 [MIM 605262], and PRX [MIM Kalaydjieva L, Gresham D, Gooding R, Heather L, Baas F, de 605725]) Jonge R, Blechschmidt K, Angelicheva D, Chandler D, Wor- sley P, Rosenthal A, King RHM, Thomas PK (2000) N-myc References downstream-regulated gene 1 is mutated in hereditary motor and sensory neuropathy-Lom. Am J Hum Genet 67:47–58 Ben Othmane K, Hentati F, Lennon F, Ben Hamida C, Blel S, Kennedy WR, Sung JH, Berry JF (1977) A case of congenital Roses AD, Pericak Vance MA, Ben Hamida M, Vance JM hypomyelination neuropathy: clinical, morphological, and (1993) Linkage of a locus (CMT4A) for autosomal recessive chemical studies. Arch Neurol 34:337–345 Charcot-Marie-Tooth disease to chromosome 8q. Hum Mol Lathrop GM, Lalouel JM, Julier C, Ott J (1985) Multilocus Genet 2:1625–1628 linkage analysis in humans: detection of linkage and esti- Bergoffen J, Scherer SS, Wang S, Scott MO, Bone LJ, Paul DL, mation of recombination. Am J Hum Genet 37:482–498 Chen K, Lensch MW, Chance PF, Fischbeck KH (1993) Con- Liehr T, Kuhlenbaumer G, Wulf P, Taylor V, Suter U, Van nexin mutations in X-linked Charcot-Marie-Tooth disease. Broeckhoven C, Lupski JR, Claussen U, Rautenstrauss B Science 262:2039–2042 (1999) Regional localization of the human epithelial mem- Boerkoel CF, Takashima H, Stankiewicz P, Garcia CA, Leber brane protein genes 1, 2, and 3 (EMP1, EMP2, EMP3) to SM, Rhee-Morris L, Lupski JR (2001) Periaxin mutations 12p12.3, 16p13.2, and 19q13.3. Genomics 58:106–108 cause recessive Dejerine-Sottas neuropathy. Am J Hum Ge- Lupski JR (1998) Charcot-Marie-Tooth disease: lessons in ge- net 68:325–333 netic mechanisms. Mol Med 4:3–11 Bolino A, Muglia M, Conforti FL, LeGuern E, Salih MA, Geor- Lupski JR, Montes de Oca-Luna R, Slaugenhaupt S, Pentao giou DM, Christodoulou K, Hausmanowa-Petrusewicz I, L, Guzzetta V, Trask BJ, Saucedo-Cardenas O, Barker DF, Mandich P, Schenone A, Gambardella A, Bono F, Quattrone Killian JM, Garcia CA, Chakravarti A, Patel PI (1991) DNA A, Devoto M, Monaco AP (2000) Charcot-Marie-Tooth duplication associated with Charcot-Marie-Tooth disease type 4B is caused by mutations in the gene encoding my- type 1A. Cell 66:219–232 otubularin-related protein-2. Nat Genet 25:17–19 Lyon G (1969) Ultrastructure study of a nerve biopsy from a Brancolini C, Marzinotto S, Edomi P, Agostoni E, Fiorentini case of early infantile chronic neuropathy. Acta Neuropathol C, Muller HW, Schneider C (1999) Rho-dependent regu- Berl 13:131–142 lation of cell spreading by the tetraspan membrane protein Matsunami N, Smith B, Ballard L, William Lensch M, Rob- Gas3/PMP22. Mol Biol Cell 10:2441–2459 ertson M, Albertsen H, Oliver Hanemann C, Muller HW, Chance PF, Bird TD, O’Connell P, Lipe H, Lalouel J-M, Lep- Bird TD, White R, Chance PF (1992) Peripheral myelin pert M (1990) Genetic linkage and heterogeneity in type 1 protein-22 gene maps in the duplication in chromosome Charcot-Marie-Tooth disease (hereditary motor and sensory 17p11.2 associated with Charcot-Marie-Tooth 1A. Nat Ge- neuropathy type 1). Am J Hum Genet 47:915–925 net 1:176–179 Chance PF, Matsunami N, Lensch W, Smith B, Bird TD (1992) Mersiyanova IV, Perepelov AV, Polyakov AV, Sitnikov VF,Dad- Analysis of the DNA duplication 17p11.2 in Charcot-Marie- ali EL, Oparin RB, Petrin AN, Evgrafov OV (2000) A new Tooth neuropathy type 1 pedigrees: additional evidence for variant of Charcot-Marie-Tooth disease type 2 is probably a third autosomal CMT1 locus. Neurology 42:2037–2041 the result of a mutation in the neurofilament-light gene. Am De Jonghe P, Mersivanova I, Nelis E, Del Favero J, Martin JJ, J Hum Genet 67:37–46 Van Broeckhoven C, Evgrafov O, Timmerman V (2001) Fur- Neitzel H (1986) A routine method for the establishment of ther evidence that neurofilament light chain gene mutations permanent growing lymphoblastoid cell lines. Hum Genet can cause Charcot-Marie-Tooth disease type 2E. Ann Neurol 73:320–326 49:245–249 Nelis E, Timmerman V, De Jonghe P, Van Broeckhoven C Dib C, Faure S, Fizames C, Samson D, Drouot N, Vignal A, (1994) Identification of a 5 splice site mutation in the PMP- Millasseau P, Marc S, Hazan J, Seboun E, Lathrop M, Gya- 22 gene in autosomal dominant Charcot-Marie-Tooth dis- pay G, Morissette J, Weissenbach J (1996) A comprehensive ease type 1. Hum Mol Genet 3:515–516 genetic map of the based on 5,264 micro- Patel PI, Roa BB, Welcher AA, Schoener-Scott R, Trask BJ, satellites. Nature 380:152–154 Pentao L, Jackson Snipes G, Garcia CA, Francke U, Shooter Dyck PJ, Lambert EH (1968) Lower motor and primary sen- EM, Lupski JR, Suter U (1992) The gene for the peripheral 250 Am. J. Hum. Genet. 70:244–250, 2002

myelin protein PMP-22 is a candidate for Charcot-Marie- Valentijn LJ, Bolhuis PA, Zorn I, Hoogendijk JE, van den Bosch Tooth disease type 1A. Nat Genet 1:159–165 N, Hensels GW, Stanton VPJ, Housman DE, Fischbeck KH, Raeymaekers P, Timmerman V, Nelis E, DeJonghe P, Hoogen- Ross DA, Nicholson GA, Meershoek EJ, Dauwerse HG, van dijk JE, Baas F, Barker DF, Martin JJ, De Visser M, Bolhuis Ommen G-J, B, Baas F (1992b) The peripheral myelin gene PA, Van Broeckhoven C (1991) Duplication in chromosome PMP-22/GAS-3 is duplicated in Charcot-Marie-Tooth disease 17p11.2 in Charcot-Marie-Tooth neuropathy type 1a (CMT type 1A. Nat Genet 1:166–170 1a). Neuromuscul Disord 1:93–97 Warner LE, Mancias P, Butler IJ, McDonald CM, Keppen L, Roa BB, Garcia CA, Suter U, Kulpa DA, Wise CA, Mueller J, Gene Koob K, Lupski JR (1998) Mutations in the early Welcher AA, Snipes GJ, Shooter EM, Patel PI (1993) Char- growth response 2 (EGR2) gene are associated with hered- cot-Marie-Tooth disease type 1A: association with a spon- itary myelinopathies. Nat Genet 18:382–384 taneous point mutation in the PMP22 gene. N Engl J Med Warner LE, Roa BB, Lupski JR (1996) Absence of PMP22 329:96–101 coding region mutations in CMT1A duplication patients: Skre H (1974) Genetic and clinical aspects of Charcot-Marie- further evidence supporting gene dosage as a mechanism for Tooth’s disease. Clin Genet 6:98–118 Charcot-Marie-Tooth disease type 1A. Hum Mutat 8:362– Taylor V, Suter U (1996) Epithelial membrane protein-2 and 365 epithelial membrane protein-3: two novel members of the Wise CA, Garcia CA, Davis SN, Heju Z, Pentao L, Patel PI, peripheral myelin protein 22 gene family. Gene 175:115– Lupki JR (1993) Molecular analyses of unrelated Charcot- 120 Marie-Tooth (CMT) disease patients suggest a high fre- Timmerman V, Nelis E, Van Hul W, Nieuwenhuijsen BW,Chen quency of the CMT1A duplication. Am J Hum Genet 53: KL, Wang S, Ben Othman K, Cullen B, Leach RJ, Hanemann 853–863 CO, De Jonghe P, Raeymaekers P, van Ommen G-J, B, Mar- Zhang H, Xu Q, Krajewski S, Krajewska M, Xie Z, Fuess S, tin J-J, Muller HW, Vance JM, Fischbeck KH, Van Broeck- Kitada S, Pawlowski K, Godzik A, Reed JC (2000) BAR: hoven C (1992) The peripheral myelin protein gene PMP- an apoptosis regulator at the intersection of caspases and 22 is contained within the Charcot-Marie-Tooth disease type Bcl-2 family proteins. Proc Natl Acad Sci USA 97:2597– 1A duplication. Nat Genet 1:171–175 2602 Valentijn LJ, Baas F, Wolterman RA, Hoogendijk JE, van den Zhao C, Takita J, Tanaka Y, Setou M, Nakagawa T, Takeda Bosch NHA, Zorn I, Gabreels-Festen AAWM, de Visser M, S, Yang H, Terada S, Nakata T, Takei Y, Saito M, Tsuji S, Bolhuis PA (1992a) Identical point mutations of PMP-22 in Hayashi Y, Hirokawa N (2001) Charcot-Marie-Tooth dis- Trembler-J mouse and Charcot-Marie-Tooth disease type ease type 2a caused by mutation in a microtubule motor 1A. Nat Genet 2:288–291 KIF1Bb. Cell 105:587–597